1. Field of the Invention
This invention relates to an electronic apparatus having a storage memory arranged to store conditions of control over the apparatus and other information.
2. Description of the Related Art
The recent advancement of electronic technology has lessened troublesome operations and processes to be performed by operators or users on various apparatuses or equipment manufactured. The electronic technology is now further advancing to provide such an apparatus that is arranged to read what is intended by the operator and to carry out automatic control accordingly.
FIG. 1 shows in a block diagram an example of a control device of a video camera which has prompted the invention of the present application. The control device is of such a system that enables the video camera to read out what is intended by the operator of the video camera and carries out automatic control according to the intention of the operator. More specifically, the control device sees where the visual line of the operator peeping into a viewfinder is directed within an image plane and causes the focal point of an optical system to be adjusted to an object of shooting at which the operator is looking. In other words, the system includes an automatic focusing control circuit which is arranged to have the optical system focused only on an object of shooting at which the operator is looking. Such a technique has been disclosed, for example, in Japanese Patent Applications No. HEI 4-314408 and No. HEI 3-218574.
Referring to FIG. 1, an infrared ray generating device 1 is arranged within a viewfinder unit to illuminate an eyeball 3 of the operator with infrared radiation through an eyepiece 2. The infrared radiation is reflected by the eyeball 3. The reflected infrared radiation is received by a photo-electric converting element 4. A visual line position analyzer 5 is connected to the photo-electric converting element 4 and is arranged to find at which objects of shooting the operator is looking. An arithmetic control device 6 which is composed of a microcomputer, etc., is connected to the visual line position analyzer 5. The arithmetic control device 6 is thus arranged to obtain information on the position of the visual line from the visual line position analyzer 5 and to compute and obtain the coordinates of the visual line within an image plane.
A character generator 7 is connected to the arithmetic control device 6 and is arranged to be used for displaying in characters the visual line position of the operator recognized by the video camera along with some other control information. A display driving device 8 is connected to the character generator 7. A signal formed by the display driving device 8 is supplied to a monitor 9 which is disposed in front of the eyepiece 2.
A lens optical system includes elements arranged to face an object of shooting 10, in alignment, in the order of a focusing lens 11, a variator lens 12, a diaphragm 13 and an image pickup photo-electric converting element 14, which is a CCD or the like. The image pickup photo-electric converting element 14 is arranged to output a video signal. The video signal is supplied to the display driving device 8. An image is displayed at the monitor 9 with the output of the character generator 7 superimposed thereon to permit sighting of it through the eyepiece 2. Further, the output of the image pickup photo-electric converting element 14 is supplied to an AF (automatic focusing) signal processing circuit 67. The output of the AF signal processing circuit 67 is supplied to a control unit 21 which will be described later. The focus is adjusted by moving the focusing lens 11 according to the output of the AF signal processing circuit 67. At that time, if the focus is to be adjusted to an object located in the position of the visual line, a distance measuring area which is not shown is shifted to the visual line position and the focusing action is carried out on the basis of information on an image located within the distance measuring area. The focusing lens 11 is connected to an actuator 15 which is a mechanism arranged to move the focusing lens 11 in the direction of an optical axis with a motor used as a drive source. The variator 12 is also arranged to be moved by an actuator 16 which is connected to the variator lens 12. Another actuator 17 is connected to the diaphragm 13 and is arranged to vary the aperture of the diaphragm 13.
These actuators 15, 16 and 17 are respectively connected to drivers 18, 19 and 20. These drivers 18, 19 and 20 are connected to the control unit 21, which is arranged to control the system and to exchange information with the arithmetic control device 6. A pull-up resistor 22 is connected between the control unit 21 and a power supply. A switch 26 is arranged between the low potential side of the pull-up resistor 22 and the ground. The arithmetic control device 6 is provided with a pull-up resistor 27 connected between the arithmetic control device 6 and a power supply. A switch 28 is disposed between the low potential side of the pull-up resistor 27 and the ground. A power supply circuit 33 is connected to the control unit 21 through lines 29, 30, 31 and 32.
The lines-29 and 30 are arranged to transmit to the control unit 21 information on a power-decreased state of a battery 36. The line 31 is for control over a supply of power to a 5 V line which is provided for the supply of the voltage of a power source of 5 V. The line 32 is arranged to constantly supply the power to the control unit 21 as long as the battery 36 is mounted. Further, the power supply circuit 33 is provided with a line 34 for outputting the power source voltage of 5 V and an unregulated line 35 for supplying the output of the battery 36 directly to the necessary part of the video camera without passing through any constant voltage circuit. The battery 36 is either a primary battery which is a manganese cell or the like and is usable only once or a secondary battery which is a nickel-cadmium battery and is rechargeable. A synchronizing signal generating circuit 37 is connected to the arithmetic control device 6 and the character generator 7. A driving circuit 38 which is connected to the synchronizing signal generating circuit 37 is arranged to drive the image pickup photoelectric converting element 14.
FIG. 2 is a circuit diagram showing the details of the power supply circuit 33. The power supply circuit 33 is arranged to convert the voltage of the battery 36 into a power supply voltage (5 V, for example) for IC circuits disposed within the video camera, to supply information on the power-decreased state (a state obtained when electric power supply capability decreases with a terminal voltage dropped) to the control unit 21 and, in a case where an instruction for bringing the supply of power to an end is given from the control unit 21, to bring the supply of power to the 5 V line 34 to an end.
The power supply circuit 33 consists of DC--DC converters 39 and 40, resistors 41 and 42 which are connected between the ground and the outputs of the DC--DC converters 39 and 40, resistors 44 and 45 which are connected between the battery 36 and the ground, a comparator 47 having the voltage of a connection node 43 between the resistors 41 and 42 and that of a connection node 46 between the resistors 44 and 45 respectively as its input signals, resistors 48 and 49 connected between the output terminal of the DC--DC converter 40 and the ground, resistors 51 and 52 connected between the battery 36 and the ground, a comparator 54 having the voltage of a connection node 50 between the resistors 48 and 49 and that of a connection node 53 between the resistors 51 and 52 respectively as its input signals, and a switch 55 which is disposed between the output terminal of the DC--DC converter 39 and the line 34.
The voltage of the battery 36 is converted into a DC voltage of 5 V by the DC--DC converter 40. The DC voltage thus obtained is divided by the resistors 41 and 42 into a reference voltage V1 and also divided by the resistors 48 and 49 into a reference voltage V2. The reference voltage V1 is arranged to be larger than the other reference voltage V2. The voltage of the battery 36 is further divided by the resistors 44 and 45 into a voltage V3 and by the resistors 51 and 52 into a voltage V4. The reference voltage V1 and the voltage V3 are compared with each other by the comparator 47 while the reference voltage V2 and the voltage V4 are arranged to be compared with each other by the comparator 54.
When the voltage V1 is found to be larger than the voltage V3, the comparator 47 outputs to the line 30 a signal indicating a power-decreased state (indicating that the battery voltage has dropped to such a level that requires replacement of the battery). Upon receipt of this signal, the control unit 21 causes the monitor 9 to make a power-decrease display through the arithmetic control device 6, the character generator 7 and the display driving device 8.
The power-decrease display is made as shown in FIG. 3. A display image plane 1801 shows a power-decrease display 1802 such as "BATT", an image 1803 of an object, and calibration markers 1804 and 1805 for adjustment of a difference in visual line function between the individual operators (hereinafter will be referred to as a personal error). The power-decrease display "BATT" 1802 is made by causing it to flicker. In using the monitor 9, when the operator closes the switch 26 of FIG. 1 to select a visual-line function personal-error adjustment mode, the visual-line function personal-error adjusting markers 1804 and 1805 are displayed on the display image plane 1801. Then, the operator first looks at the marker 1804 and closes the switch 28. By this operation, the position of a visual line which is obtained when the operator looks at the marker 1804 is confirmed. Following this, another visual line position which is obtained when the operator looks at the other marker 1805 is confirmed.
Then, "information on coincidence of the recognition by the apparatus with the visual lines of the operator" obtained when the operator looks at the visual-line function personal-error adjusting markers 1804 and 1805 is stored in a storage part within the arithmetic control device 6. After that, each visual line of the operator is examined on the basis of this information.
When the voltage of the battery 36 further drops until the other reference voltage V2 becomes higher than the voltage V4 after the power-decrease display is made, the comparator 54 outputs to the line 29 a signal for shutting off the power. According to this signal, the control unit 21 opens the switch 55 to cut off the supply of power to each block to forcibly bring the operation of the system to a stop, so that the system can be prevented from coming out of order or from malfunctioning.
In cases where an apparatus is arranged to observe the visual lines of the operators and to control its actions according to these visual lines, the control must be performed after adjustment is made to the personal error of each of the operators according to the personal error of each operator, because the visual lines of one operator differ from those of another.
FIG. 4 is a block diagram showing in detail the internal arrangement of the arithmetic control device 6. The arithmetic control device 6 consists of a storage part 6a which is arranged to carry out an arithmetic process for control and includes a temporary information storing device and another storage part 6b which is arranged to store information on a personal error or nontemporary information which is stored as long as the information is not erased by the operator or a person adjusting the camera. The storage part 6b is composed of an element such as an EEPROM or the like that inhibits erasing and writing unless some special process is performed. The contents of the storage part 6b cannot be updated without using a specific program or a specific instruction. The information on the personal error thus stored is used for operations to be performed thereafter.
However, with the video camera arranged in the manner as described above, the provision of the function of adjusting the personal error of the visual line of the operator tends to bring about the following problem.
Since the duration time of one battery is only one or two hours in general, the power is frequently shut off. The personal error adjusting function, on the hand, can be carried out any time as desired. In a case where the information on the personal error is to be stored in an element such as an EEPROM or the like that is dependent on a run command coming from an external software, if the supply of power becomes unstable while the storing action on the storage part is still in process, some malfunction tends to take place. For example, in such a case, some unspecified figure might be written in as data other than the data of a predetermined address, or some part other than a designated part might be erased in error. Further, if the power is actually shut off due to a power decrease within a period of limited time necessary for writing, it becomes hardly possible to correctly judge the content of the storage part to be a value obtained prior to the data currently applicable, or to be representing a state obtained after completion of rewriting or to be a totally wrong value. Under such a condition, the reliability of the data in storage itself would be lost.
If any abnormal data is stored in the storage part in this manner, a part of a program might become hardly executable. In such a case, even if the operator makes adjustment according to predetermined procedures, the apparatus might fail to smoothly operate.